colloque lille2017 sequence-9-2-aammonia-eng_ruud
TRANSCRIPT
Ammonia (NH3) in Norwegian dairy herds
Lars Erik RuudAssociate professor
NHH
H
• Dairy• Advisory service
Ammonia – NH3
• A poisonous gas with distinct and unpleasant odour• Has local effects on mucosal surfaces
– Associated with respiratory problems in animals and humans• Negative environmental effects; acidifying, eutrophying
and is a source of the greenhouse gas N2O
• Density is approx. 59% of atmospheric air
NH3
ppm Symptoms7-10 Negative effects of long term exposure5-15 Odour threshold humans20 Irritation of eyes in broiler30 Irritation of eyes and respiratory tract in animals and humans50 Reduced production/ yield, watery eyes70 Fast reduction of growth and very poor feed utilization100 Increased respiratory rate, edema of the lungs5000 Lethal in minutes
Several studies shows negative effects:
Occupational exposure limit (N): 15 ppm (8h/day) Regulations on keeping cattle: 10 ppm
[Gustavsson, 1988]
What is the source of NH3?
Emmission
Production
The source of NH3?
During degradationof proteins and nucleic acids nitrogenous waste is formed
AmmoniaUreaUric acid
[Mod. after Gustavsson, 1988]
The source of NH3?
Stable atmosphere(emmission)
Litter/ manure(production)
During degradationof proteins and nucleic acids nitrogenous wastesare formed
AmmoniaUreaUric acid
NH4+
AmmoniumNH3
Ammonia
pH –increase
pH –decrease
GaseousNH3
[Mod. after Gustavsson, 1988]NH3 -concentration
in the stable atmosphere
Ventilation
NH3- consentration varies with• pH in manure (animal species, feeding etc.)• N-surplus in manure (feeding)• Air temperature and relative humidity• Dry matter in manure• C/N – ratio in bedding material• Soiled area (m2 wet by urine)• Ventilation
• => Housing design («technical sorroundings»)
Objective• To measure NH3-concentration in Norwegian
dairy herds• Investigate associations between housing
design and NH3-consentration
Method• Mean for recorded value
measured central on feed bunk, activity area and resting place= NH3-consentration
• «Barn design», cleanliness, feeding and more was recordedduring one winter-time visit(minimum ventilation rate)
t-test/ ANOVA was used to evaluatedifferences between different design etc
[Micro IV, GfG instruments]
Material• 62 herds from the central east Mjøs-region (n=31),
Nordland (n=6) or north-west Norway (coast) and Sør-Trøndelag (n=25)
• Visited once by a trained technician from Tine or a technician from HINN during the winter 2012 – 2013
• 109 ± 59,8 animals; 49 ± 21,6 lactating dairy cows• 2002 [1975 – 2012]; 87 % loose housing (free stalls)• One herd was excluded because of extreme values due
to aeration of NH3-treated straw inside of the barn60°N
70°N
Results (n = 61 herds)
• Mean NH3-concentration: 4,5 ppm [0 – 20,2 ppm]
Regulation on keeping cattle; 90 % <10 ppm
Occupational limit; 98 % <15 ppm
Occupational limit (<2002 -> 2024); 2 % >15 ppm
«Negative» results (no associations)• Feeding (composition of the meny)
– TMR/PMR vs roughage & concentrate fed separately• Herd size• Housing system (loose housing vs tie stalls)• Flooring (slatted floor vs solid floor)• Open vs closed connection between manure storage and the animal
room (traditionally manure are stored in cellar)• Sloped alley floor vs flat floor• Animal crowding/ m2 and m3
• Type of ventilation system; natural, guided natural or mechanical• Location of ventilation fan; cellar, wall or pipe
«Positive» results (significant association)• Fully insulated > non-insulated and low-insulated
buildings• System for urine drainage < without• RH% + indoor temperature < 90
– capacity/ adjustment of the ventilation system• CO2 (capacity/ adjustment of the ventilation system)• Low indoor temperature < high indoor temperature• Clean stalls < dirty stalls (cleanliness and management)
Tendencies (p = 0,06-0,10)
• Compost bed < other housing systems• Natural ventilation < mechanical ventilation
Discussion• Lower concentration than expected (feared)
Hygiene=> the main source for NH3-formation is removed
Urine drainage=> a source for NH3-formation is removed
Compost bed=> manure is absobed, pH, C/N-ratio
RH% + ind. temp (90-rule) => Ventilation capacity/ adjustment = Increased air exchange
Uninsulated => NH3 is evacuated through roofopenings because NH3 has lower density comparedto atmospherical air
• No effect of fan in cellar or open connectionon on NH3-concentration – …because density of NH3 is < density of atm. air
• Confirmed by the lower NH3 concentrations when naturally ventilated (openridge)
• NB! Other gases have other effects, e.g. H2S (hydrogen sulfide) that has a higher density than atm.air– «Manure gases» ≠ NH3
– Different gases has to be handled independently
• The housing design may influence on NH3 concentrations, however also cleaning routines (management) has positive effects
Conclusion• Uninsulated/ low insulation• Natural ventilation• High ventilation rate (>90)• Cleanliness routines
• Urine draining systems• Reccomended ventilation rates
for fully insulated barns
Important to achieve low concentrations
Worth further investigation
Thank you for your attention!
Cow cleanliness
Stall cleanliness• 1 - Clean• 2 - Some dirt• 3 - Dirty• 4 - Very dirty
Mechanical scraper on slatted floor
…may be automatic as well !